Publications by authors named "Kar Seng Sim"

RNAseq data can be used to infer genetic variants, yet its use for estimating genetic population structure remains underexplored. Here, we construct a freely available computational tool (RGStraP) to estimate RNAseq-based genetic principal components (RG-PCs) and assess whether RG-PCs can be used to control for population structure in gene expression analyses. Using whole blood samples from understudied Nepalese populations and the Geuvadis study, we show that RG-PCs had comparable results to paired array-based genotypes, with high genotype concordance and high correlations of genetic principal components, capturing subpopulations within the dataset.

View Article and Find Full Text PDF

Genomic researchers increasingly utilize commercial cloud service providers (CSPs) to manage data and analytics needs. CSPs allow researchers to grow Information Technology (IT) infrastructure on demand to overcome bottlenecks when combining large datasets. However, without adequate security controls, the risk of unauthorized access may be higher for data stored on the cloud.

View Article and Find Full Text PDF

The therapeutic efficacy of tamoxifen is predominantly mediated by its active metabolites 4-hydroxy-tamoxifen and endoxifen, whose formation is catalyzed by the polymorphic cytochrome P450 2D6 (CYP2D6). Yet, known CYP2D6 polymorphisms only partially determine metabolite concentrations in vivo. We performed the first cross-ancestry genome-wide association study with well-characterized patients of European, Middle-Eastern, and Asian descent (n = 497) to identify genetic factors impacting active and parent metabolite formation.

View Article and Find Full Text PDF
Article Synopsis
  • - The study investigates the role of low-frequency genetic variants in telomere length (LTL) among 25,533 Singapore Chinese individuals, emphasizing their potential link to chronic diseases and mortality.
  • - Three specific variants near the POT1, TERF1, and STN1 genes were found to significantly affect LTL, with one variant (rs79314063) showing a notably strong effect independent of common variants.
  • - The research indicates that genetically determined LTL is particularly associated with lung adenocarcinoma, and one variant (rs79617270) is linked to increased cancer mortality and may influence colon cancer risk through its effect on LTL.
View Article and Find Full Text PDF
Article Synopsis
  • Exfoliation syndrome is a systemic disorder characterized by the buildup of abnormal protein aggregates in the eye, leading to increased risk of glaucoma and potential blindness.
  • The study aimed to explore the association between exfoliation syndrome and rare genetic variants that could affect protein function, using whole-exome sequencing on participants from 14 countries over 20 years.
  • Results showed that individuals with exfoliation syndrome were more likely to have harmful genetic variants in the CYP39A1 gene compared to those without the condition, indicating a potential genetic factor in the disorder.
View Article and Find Full Text PDF
Article Synopsis
  • Primary open-angle glaucoma is more common and severe in people of African descent compared to those of European or Asian ancestry, yet they are often overlooked in genetic research on this condition.
  • The study conducts a genome-wide association study (GWAS) involving nearly 10,000 participants from various countries to identify genetic links to the disease.
  • Results suggest significant genetic variants associated with primary open-angle glaucoma, highlighting the need for more focused research on affected populations for better understanding and treatment options.
View Article and Find Full Text PDF

Genetic factors underlying leukocyte telomere length (LTL) may provide insights into telomere homeostasis, with direct links to disease susceptibility. Genetic evaluation of 23,096 Singaporean Chinese samples identifies 10 genome-wide loci (P < 5 × 10). Several of these contain candidate genes (TINF2, PARP1, TERF1, ATM and POT1) with potential roles in telomere biology and DNA repair mechanisms.

View Article and Find Full Text PDF
Article Synopsis
  • A study investigated the role of protein-coding variants in leprosy susceptibility among Han Chinese, involving 7,048 leprosy patients and 14,398 healthy controls.
  • Researchers identified seven significant coding variants, including two rare variants linked to higher risk of developing leprosy, along with low-frequency and common variants.
  • Findings suggest that these protein-coding variants, especially the rare and low-frequency ones, affect skin barrier functions and immune responses, underlining the importance of studying protein-coding variants for understanding complex diseases like leprosy.
View Article and Find Full Text PDF
Article Synopsis
  • Exfoliation syndrome (XFS) is a significant risk factor for secondary glaucoma, contributing to blindness globally, with known genetic variants in LOXL1 and CACNA1A linked to the condition.
  • Researchers conducted a study analyzing samples from multiple countries, discovering a rare protective allele at LOXL1 and refining its association, which had been previously inconsistent across different populations.
  • A genome-wide association study identified seven significant genetic loci related to XFS, providing new insights into its biological mechanisms and emphasizing the role of rare LOXL1 variants in the disease's development.
View Article and Find Full Text PDF

Meningococcal disease (MD) remains an important infectious cause of life threatening infection in both industrialized and resource poor countries. Genetic factors influence both occurrence and severity of presentation, but the genes responsible are largely unknown. We performed a genome-wide association study (GWAS) examining 5,440,063 SNPs in 422 Spanish MD patients and 910 controls.

View Article and Find Full Text PDF
Article Synopsis
  • * A genome-wide association study identified significant associations with 51 SNPs in the class II MHC region on chromosome 6, particularly focusing on the SNP rs9277378 linked to the HLA-DPB1 gene, indicating a strong genetic risk factor for NKTCL.
  • * The study suggests that specific amino acid residues in the HLA-DPB1 may play a crucial role in the risk of developing NKTCL, distinguishing this risk from associations with Epstein-Barr virus infection.
View Article and Find Full Text PDF

Polypoidal choroidal vasculopathy (PCV), a subtype of 'wet' age-related macular degeneration (AMD), constitutes up to 55% of cases of wet AMD in Asian patients. In contrast to the choroidal neovascularization (CNV) subtype, the genetic risk factors for PCV are relatively unknown. Exome sequencing analysis of a Han Chinese cohort followed by replication in four independent cohorts identified a rare c.

View Article and Find Full Text PDF
Article Synopsis
  • Primary angle closure glaucoma (PACG) is a key cause of blindness, prompting a large-scale study involving over 10,000 PACG patients and nearly 30,000 controls across multiple continents.
  • The study identified five new genetic loci associated with PACG risk, each with significant statistical results (e.g., EPDR1 with an odds ratio of 1.24 and a P-value of 5.94 × 10(-15)).
  • Additionally, three previously known genetic loci were confirmed, enhancing the understanding of the genetic factors underlying PACG.
View Article and Find Full Text PDF
Article Synopsis
  • Exfoliation syndrome (XFS) is a common cause of a type of eye disease called open-angle glaucoma.
  • Researchers studied the DNA of nearly 1,500 people with XFS and compared it to over 1,100 healthy people from Japan, and then looked at even more data from around the world.
  • They found a new gene that seems to increase the chances of getting XFS and confirmed another gene that behaves differently in people from different backgrounds.
View Article and Find Full Text PDF
Article Synopsis
  • Primary open-angle glaucoma is a leading cause of permanent blindness and involves changes in the optic nerve structure, particularly the optic disc and neuroretinal rim.
  • The International Glaucoma Genetics Consortium analyzed genetic data from over 24,000 individuals to explore relationships between specific genetic locations (loci) and optic nerve measurements called disc area and cup area.
  • They discovered 20 new genetic loci linked to these measurements, which may enhance understanding of glaucoma mechanisms and lead to new research on treatment and prevention.
View Article and Find Full Text PDF

Age-related macular degeneration (AMD) is a major cause of blindness, but presents differently in Europeans and Asians. Here, we perform a genome-wide and exome-wide association study on 2,119 patients with exudative AMD and 5,691 controls, with independent replication in 4,226 patients and 10,289 controls, all of East Asian descent, as part of The Genetics of AMD in Asians (GAMA) Consortium. We find a strong association between CETP Asp442Gly (rs2303790), an East Asian-specific mutation, and increased risk of AMD (odds ratio (OR)=1.

View Article and Find Full Text PDF

Enteric fever affects more than 25 million people annually and results from systemic infection with Salmonella enterica serovar Typhi or Paratyphi pathovars A, B or C(1). We conducted a genome-wide association study of 432 individuals with blood culture-confirmed enteric fever and 2,011 controls from Vietnam. We observed strong association at rs7765379 (odds ratio (OR) for the minor allele = 0.

View Article and Find Full Text PDF
Article Synopsis
  • Glaucoma causes irreversible blindness and is primarily linked to optic nerve degeneration, with a focus on the vertical cup-disc ratio (VCDR) as a key indicator.
  • A meta-analysis by the International Glaucoma Genetics Consortium revealed 10 new genetic loci tied to VCDR variation among large groups of individuals from European and Asian backgrounds.
  • The findings indicate that Caucasian individuals in the highest risk group have a 2.5-fold greater chance of developing primary open-angle glaucoma, significantly enhancing the understanding of the genetic factors involved in this eye condition.
View Article and Find Full Text PDF

Whole-genome sequencing across multiple samples in a population provides an unprecedented opportunity for comprehensively characterizing the polymorphic variants in the population. Although the 1000 Genomes Project (1KGP) has offered brief insights into the value of population-level sequencing, the low coverage has compromised the ability to confidently detect rare and low-frequency variants. In addition, the composition of populations in the 1KGP is not complete, despite the fact that the study design has been extended to more than 2,500 samples from more than 20 population groups.

View Article and Find Full Text PDF

Primary angle closure glaucoma (PACG) is a major cause of blindness worldwide. We conducted a genome-wide association study including 1,854 PACG cases and 9,608 controls across 5 sample collections in Asia. Replication experiments were conducted in 1,917 PACG cases and 8,943 controls collected from a further 6 sample collections.

View Article and Find Full Text PDF

We performed a two-stage genome-wide association study of IgA nephropathy (IgAN) in Han Chinese, with 1,434 affected individuals (cases) and 4,270 controls in the discovery phase and follow-up of the top 61 SNPs in an additional 2,703 cases and 3,464 controls. We identified associations at 17p13 (rs3803800, P = 9.40 × 10(-11), OR = 1.

View Article and Find Full Text PDF

Kawasaki disease is a systemic vasculitis of unknown etiology, with clinical observations suggesting a substantial genetic contribution to disease susceptibility. We conducted a genome-wide association study and replication analysis in 2,173 individuals with Kawasaki disease and 9,383 controls from five independent sample collections. Two loci exceeded the formal threshold for genome-wide significance.

View Article and Find Full Text PDF

Recent reports have identified a north-south cline in genetic variation in East and South-East Asia, but these studies have not formally explored the basis of these clinical differences. Understanding the origins of these variations may provide valuable insights in tracking down the functional variants in genomic regions identified by genetic association studies. Here we investigate the genetic basis of these differences with genome-wide data from the HapMap, the Human Genome Diversity Project and the Singapore Genome Variation Project.

View Article and Find Full Text PDF